Owen Duffy wrote:
Cecil, I don't understand what you mean by 'virtual impedance', why and how
it differs from equivalent impedance (being the complex ratio of V/I at a
point), and why it has these magical relection properties. Perhaps it is
just an invention to support your proposition.

The IEEE Dictionary seemingly goes out of its way to
try to emphasize the difference between a virtual
impedance and a physical impedor. Obviously, there is
a difference between a physical resistor and the ratio
of voltage to current called resistance where no physical
resistor exists. One is the (A) definition and the other
is the (B) definition. A virtual resistance does not
dissipate power. What? A dissipationless resistance?

If no physical impedance discontinuity exists, there can
be no reflections. V/I ratios, by themselves, with no
associated physical impedances, are a result, and not the
cause of anything. (The exception to that statement is a
source.)

The impedance looking into a transmission line is a virtual
impedance caused by system parameters. It is a result -
incapable of causing anything. Unless it is located at a
physical impedance discontinuity, absolutely nothing happens
because of the V/I ratio.
--
73, Cecil http://www.w5dxp.com